The agent may know the task better than anyone else in the process, yet only the owner of the local session can interact with it.
Context, tools, sessions, executors, and permissions are not formal parts of the process. The team cannot continue someone else’s work, address the actual executor directly, or safely expose a harness to others.
Reviewer.Agent gets read-only permissions and a shared identity; QA or the pull request author can ask it a follow-up directly instead of using the local session owner as a proxy.